SR 103 was created in the 1964 highway renumbering, replacing the earlier Secondary State Highway 12A (SSH 12A) that was created in 1937 to serve Long Beach and Ocean Park, later extended north in 1991 to serve Leadbetter Point State Park.

In 2011, WSDOT calculated that the busiest section of the highway was at 10th Street in Downtown Long Beach, serving 7,900 vehicles, while the least busiest section was the entrance to Leadbetter Point State Park, serving 270 vehicles.

[5] SSH 12A was established in 1937 during the creation of the primary and secondary state highway system, traveling north from US 101 in Seaview through Long Beach to Ocean Park.

[6][7] During the 1964 highway renumbering, SR 103 replaced SSH 12A on its 11.09-mile-long (17.85 km) route,[8][9] serving the Long Beach Peninsula.

[10] SR 103 was extended further north to serve Leadbetter Point State Park in 1991, increasing the total distance of the highway to the current 19.97-mile-long (32.14 km) route.